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Jun 10, 2024, 3:08:01 PMJun 10
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Kicking the can down the road: understanding the effects of delaying the deployment of stratospheric aerosol injection

Brody, E., Visioni, D., Bednarz, E. M., Kravitz, B., MacMartin, D. G., Richter, J. H., & Tye, M. R. (2024). Kicking the can down the road: understanding the effects of delaying the deployment of stratospheric aerosol injection. Environmental Research: Climate.


Climate change is a prevalent threat, and it is unlikely that current mitigation efforts will be enough to avoid unwanted impacts. One potential option to reduce climate change impacts is the use of stratospheric aerosol injection (SAI). Even if SAI is ultimately deployed, it might be initiated only after some temperature target is exceeded. The consequences of such a delay are assessed herein. This study compares two cases, with the same target global mean temperature of ~1.5°C above preindustrial, but start dates of 2035 or a "delayed" start in 2045. We make use of simulations in the Community Earth System Model version 2 with the Whole Atmosphere Coupled Chemistry Model version 6 (CESM2-WACCM6), using SAI under the SSP2-4.5 emissions pathway. We find that delaying the start of deployment (relative to the target temperature) necessitates lower net radiative forcing (-30%) and thus larger sulfur dioxide injection rates (+20%), even after surface temperatures converge, to compensate for the extra energy absorbed by the Earth system. Southern hemisphere ozone is higher from 2035 to 2050 in the delayed start scenario, but converges to the same value later in the century. However, many of the surface climate differences between the 2035 and 2045 start simulations appear to be small during the 10-25 years following the delayed SAI start, although longer simulations would be needed to assess any longer-term impacts in this model. In addition, irreversibilities and tipping points that might be triggered during the period of increased warming may not be adequately represented in the model but could change this conclusion in the real world.

Improving risk governance strategies via learning: a comparative analysis of solar radiation modification and gene drives

Grieger, K., Wiener, J. B., & Kuzma, J. (2024). Improving risk governance strategies via learning: a comparative analysis of solar radiation modification and gene drives. Environment Systems and Decisions, 1-14.


Stratospheric aerosol injection (SAI) and gene drive organisms (GDOs) have been proposed as technological responses to complex entrenched environmental challenges. They also share several characteristics of emerging risks, including extensive uncertainties, systemic interdependencies, and risk profiles intertwined with societal contexts. This Perspective conducts a comparative analysis of the two technologies, and identifies ways in which their research and policy communities may learn from each other to inform future risk governance strategies. We find that SAI and GDOs share common features of aiming to improve or restore a public good, are characterized by numerous potential ecological, societal, and ethical risks associated with deep uncertainty, and are challenged by how best to coordinate behavior of different actors. Meanwhile, SAI and GDOs differ in their temporal and spatial mode of deployment, spread, degree and type of reversibility, and potential for environmental monitoring. Based on this analysis, we find the field of SAI may learn from GDOs by enhancing its international collaborations for governance and oversight, while the field of GDOs may learn from SAI by investing in research focused on economics and decision-modeling. Additionally, given the relatively early development stages of SAI and GDOs, there may be ample opportunities to learn from risk governance efforts of other emerging technologies, including the need for improved monitoring and incorporating aspects of responsible innovation in research and any deployment.

Modeling 2020 regulatory changes in international shipping emissions helps explain 2023 anomalous warming

Quaglia, I., & Visioni, D. (2024). Modeling 2020 regulatory changes in international shipping emissions helps explain 2023 anomalous warming. EGUsphere, 2024, 1-19.


The summer of 2023 has seen an anomalous increase in temperatures even when considering the ongoing greenhouse-gases driven warming trend. Here we demonstrate that regulatory changes to sulfate emissions from international shipping routes, which resulted in a significant reduction in sulfate particulate released during international shipping starting on January 1 2020, have been a major contributing factor to the monthly surface temperature anomalies during the last year. We do this by including in Community Earth System Model (CESM2) simulations the appropriate changes to emission databases developed for the Climate Model Intercomparison Project version 6 (CMIP6). The aerosol termination effect simulated by the updated CESM2 simulations is consistent with observations of both radiative forcing and surface temperature, manifesting a similar delay as the one observed in observational datasets between the implementation of the emission changes and the anomalous increase in warming. Our findings highlight the importance of considering realistic near-future changes in short-lived climate forcers for future climate projections, such as for CMIP7, for an improved understanding and communication of short-term climatic changes.

Comparison of marine cloud brightening in large eddy simulations

Smith, W. M. (2024). Comparison of marine cloud brightening in large eddy simulations (No. EGU24-4102). Copernicus Meetings.


Modelling of marine cloud brightening (MCB), a form of solar radiation modification, has thus far proven challenging due to the incongruous nature of the scales required. The microphysics of the cloud droplets and aerosols can only be resolved at really small scales, but just as important are the large-scale impacts on circulation and radiation. Large eddy simulations (LES) seem best placed to deal with this problem; they can resolve circulation an turbulence, but also have small enough grid boxes that useful parametrisation of microphysics can be made. When coupled to parcel models their representation of microphysical processes can be improved even further, although at a computational cost. There have been multiple studies of MCB in LES so far, but with wide-ranging background conditions and experimental designs. This leads to varying results that are challenging to compare. The aim of this study is to directly compare the results of at least two LES models, MONC and DALES, for an MCB experiment. They will first be compared with a historic data set, before being configured to ran the MCB experiment. It is hoped that MONC can also be coupled to a parcel model to improve its representation of cloud microphysics.

Changes in coastal upwelling in the northern Gulf of Guinea under Stratospheric Aerosol Injection

Ayissi, F. F. B. K., Da-Allada, C. Y., Baloïtcha, E., Worou, L. O., & Tilmes, S. (2024). Changes in Coastal Upwelling in the Northern Gulf of Guinea under Stratospheric Aerosol Injection. Regional Studies in Marine Science, 103607.


This study aims to assess the impact of Stratospheric Aerosol Injection (SAI) on the coastal upwelling in the northern Gulf of Guinea based, on upwelling index computation and using the Community Earth System Model from the Geoengineering Large Ensemble (GLENS) project. GLENS project targets not only maintaining the global temperature but also the interhemispheric and equator-to-pole temperature gradient at their 2020 values by preventing part of the solar radiation from reaching the Earth’s surface under a RCP8.5 scenario. The results show that along the coast of the northern Gulf of Guinea main upwelling cells are to the east of Cape Palmas and Cape Three Points, and that upwelling is most intense in the Ghana region compared to Côte d’Ivoire region. It is also found that Ekman transport associated with geostrophic flow can explain a large part of the intensity of the coastal upwelling in the northern Gulf of Guinea. Geostrophic flow towards the coast reduces upwelling intensity, especially in the Ghana region. In the context of global warming, boreal summer upwelling intensity decreases all along the coast by 6% (with 2% in the Côte d’Ivoire region and a more significant decrease of 10% in the Ghana region). This decrease in upwelling intensity is linked to the intensification of geostrophic flow towards the coast. Under SAI, coastal upwelling intensity is still decreased by 5% along the coast (with 3% in the Côte d’Ivoire region and 6% in the Ghana region), but this decrease is relatively weak compared to global warming. This increase in upwelling intensity compared with climate change, especially in Ghana, is associated with a 50% reduction in the effect of geostrophic flow limitation with respect to global warming. During the minor upwelling season, the upwelling intensity increases, due to Ekman transport, both under the climate change and SAI.


The Solar Geoengineering Updates Newsletter (May'2024)
Solar Geoengineering Updates

6 days ago · Andrew Lockley
What Other Sectors Can Teach Us: Insights For Effective Communication In Solar Geoengineering (DSG)
Could spraying sea salt into the clouds cool the planet (The Washington Post)
California City Leaders End Cloud-Brightening Test, Overruling Staff (The New York Times)
Global Cooling Forecasts from Stratospheric Aerosol Injection (Planet Parasol)
How did a sudden reduction in shipping pollution inadvertently stoke global warming? (Los Angeles Times)


Chemical and Climatic Impacts of Solid Particles for Stratospheric Solar Climate Intervention


(NEW) Solar Climate Intervention Virtual Symposia#11 | 14 June 2024 | Online 
Governing Prometheus. Ethical Reflections On Risk & Uncertainty In Solar Climate Engineering Research | 19 June 2024 | TU Delft University 
Fourteenth GeoMIP Workshop | 10-12 July 2024 | Ithaca, USA
RFF 2024 SRM Social Science Workshop: Cooperative vs. Non-Cooperative Interventions | 19-20 September 2024 | Washington, DC.

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Shall We Whiten Clouds | ToSaveTheWorld

"Hugh Hunt, Daniel Rosenfeld, and Steven Rogak are all engineers who are eagerly studying the potential. use of salt water spray to whiten clouds and reflect sunshine back into space, thereby reducing global warming. Adele Buckley is an engineer who is skeptical about the value of trying to keep the Arctic frozen at this time."

Sharing Sámi Experiences: Indigenous Voices on Climate Intervention Research | SilverLining

"During the United Nations Permanent Forum on Indigenous Issues' Twenty-third Session, the Sámi Parliament of Finland, in partnership with Operaatio Arktis, SilverLining, and Green Africa Youth Organization, held "Sharing Sámi Experiences: Indigenous Voices on Climate Intervention Research," at the Permanent Mission of Finland to the UN. 

Indigenous peoples are at the forefront of climate impacts, yet they possess invaluable traditional knowledge and practices through which they foster relationships with ecosystems. Indigenous knowledge also has the potential to contribute significantly to efforts seeking to address different facets of global warming– including climate intervention research.

This event highlights the critical importance of integrating Indigenous perspectives, knowledge, and participation into climate intervention research. At the same time, it underscores the urgent need to center Indigenous knowledge, perspectives, and rights in global efforts to address climate change. 

The event aimed to provide a safer space for Indigenous voices, policymakers and climate scientists, as well as experts on climate intervention research and international governance, to discuss the scientific context of climate interventions and their potential roles in relation to 1.5°C of warming."

Inside the Extreme Plan to Refreeze the Arctic | WSJ Future of Everything | The Wall Street Journal

“A method normally used to create ice-skating rinks is now coming to the rescue of melting sea ice in the Arctic. Since satellite records began in 1979, summer Arctic sea ice has shrunk by around 13% per decade. Could making more ice be a potential solution to this issue?”

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